Modeling of Photon Recycling in GaN-Devices

The strength of recombination radiation reabsorption in GaN is discussed. For material comparisons a distance-dependent radiative recombination transfer function F(u) is introduced. In spite of high absorption rates of GaN, calculations predict ca. one order of magnitude higher photon recycling efficiency in GaN than in GaAs. Simulations of 2H-GaN p −i −n structures predict appearance of S-shaped forward I/V characteristics due to the generation of extra carriers in the base center. The study of GaN bipolar transistors shows that the radiative recombination will reduce the carrier lifetimes in the base and thereby restrict essentially the achievable current gains.